778 research outputs found
Streaming Reconstruction from Non-uniform Samples
We present an online algorithm for reconstructing a signal from a set of
non-uniform samples. By representing the signal using compactly supported basis
functions, we show how estimating the expansion coefficients using
least-squares can be implemented in a streaming manner: as batches of samples
over subsequent time intervals are presented, the algorithm forms an initial
estimate of the signal over the sampling interval then updates its estimates
over previous intervals. We give conditions under which this reconstruction
procedure is stable and show that the least-squares estimates in each interval
converge exponentially, meaning that the updates can be performed with finite
memory with almost no loss in accuracy. We also discuss how our framework
extends to more general types of measurements including time-varying
convolution with a compactly supported kernel
A class of M-Channel linear-phase biorthogonal filter banks and their applications to subband coding
This correspondence presents a new factorization for linearphase biorthogonal perfect reconstruction (PR) FIR filter banks. Using this factorization, we propose a new family of lapped transform called the generalized lapped transform (GLT). Since the analysis and synthesis filters of the GLT are not restricted to be the time reverses of each other, they can offer more freedom to avoid blocking artifacts and improve coding gain in subband coding applications. The GLT is found to have higher coding gain and smoother synthesis basis functions than the lapped orthogonal transform (LOT). Simulation results also demonstrated that the GLT has significantly less blocking artifacts, higher peak signal-tonoise ratio (PSNR), and better visual quality than the LOT in image coding. Simplified GLT with different complexity/performance tradeoff is also studied. © 1999 IEEE.published_or_final_versio
The Singular Values of the GOE
As a unifying framework for examining several properties that nominally
involve eigenvalues, we present a particular structure of the singular values
of the Gaussian orthogonal ensemble (GOE): the even-location singular values
are distributed as the positive eigenvalues of a Gaussian ensemble with chiral
unitary symmetry (anti-GUE), while the odd-location singular values,
conditioned on the even-location ones, can be algebraically transformed into a
set of independent -distributed random variables. We discuss three
applications of this structure: first, there is a pair of bidiagonal square
matrices, whose singular values are jointly distributed as the even- and
odd-location ones of the GOE; second, the magnitude of the determinant of the
GOE is distributed as a product of simple independent random variables; third,
on symmetric intervals, the gap probabilities of the GOE can be expressed in
terms of the Laguerre unitary ensemble (LUE). We work specifically with
matrices of finite order, but by passing to a large matrix limit, we also
obtain new insight into asymptotic properties such as the central limit theorem
of the determinant or the gap probabilities in the bulk-scaling limit. The
analysis in this paper avoids much of the technical machinery (e.g. Pfaffians,
skew-orthogonal polynomials, martingales, Meijer -function, etc.) that was
previously used to analyze some of the applications.Comment: Introduction extended, typos corrected, reference added. 31 pages, 1
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